WARM SPRING, Ore. — Oregon officials sent more than 100 firefighters to help protect buildings being threatened by a central Oregon wildfire on the Warm Springs Indian Reservation.

The Oregon State Fire Marshal Office Incident Management Team that arrived Friday will help protect the communities of Simnasho, Mutton Mountain and Indian Head Canyon.

The 53-square-mile (137-square-kilometer) wildfire that started Tuesday has destroyed one unoccupied residence and several unoccupied historic buildings and outbuildings.

Officials say the human-caused fire is burning through grass, brush and timber slash.

About 240 personnel are assigned to the blaze that’s about 15 percent contained.

Officials say air tankers and helicopters have been dropping retardant and water as part of a strategy to prevent the wildfire’s spread.

People at Kah-Nee-Ta Resort are being told to be aware there is a wildfire so they can be ready to leave if necessary.